book3s64/hash: Add hash_debug_pagealloc_add_slot() function

book3s64/hash: Add hash_debug_pagealloc_add_slot() function

This adds hash_debug_pagealloc_add_slot() function instead of open
coding that in htab_bolt_mapping(). This is required since we will be
separating kfence functionality to not depend upon debug_pagealloc.

No functionality change in this patch.

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/026f0aaa1dddd89154dc8d20ceccfca4f63ccf79.1729271995.git.ritesh.list@gmail.com